Wildfires drive interannual variability of organic carbon aerosol in the western U.S. in summer

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Read Full Article (file size: 174876 bytes) Cited by GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L16816, doi:10.1029/2007GL030037, 2007 Wildfires drive interannual variability of organic carbon aerosol in the western U.S. in summer Dominick V. Spracklen School of Engineering and Applied Sciences, Harvard University, Cambridge, USA Jennifer A. Logan School of Engineering and Applied Sciences, Harvard University, Cambridge, USA Loretta J. Mickley School of Engineering and Applied Sciences, Harvard University, Cambridge, USA Rokjin J. Park School of Engineering and Applied Sciences, Harvard University, Cambridge, USA Rosemarie Yevich School of Engineering and Applied Sciences, Harvard University, Cambridge, USA Anthony L. Westerling School of Engineering, University of California, Merced, California, USA Dan A. Jaffe Interdisciplinary Arts and Sciences, University of Washington Bothell, Bothell, Washington, USA Abstract Forest wildfire area burned in the western U.S. has increased in recent decades resulting in a substantial organic carbon (OC) source with large interannual variability. We derive OC emissions from wildfires using data for area burned for 1980–2004 and ecosystem specific fuel loadings. For the period 1989–2004 we analyze OC observations in the western U.S. from the IMPROVE network and use a global chemical transport model to simulate OC concentrations. Modeled and observed OC concentrations are highly correlated when we use interannually varying fire emissions (R² = 0.88); the correlation is smaller with climatological emissions (R² = 0.4). We estimate that the observed increase in wildfire activity after the mid 1980s has caused mean OC concentrations in summer over the western U.S. to increase by 30% relative to 1970–1984. In the coming decades, climate change will likely cause further increases in wildfires resulting in increased OC concentrations with implications for health and visibility. Received 15 March 2007; accepted 16 July 2007; published 25 August 2007. Keywords: biomass burning; aerosols; climate change. Index Terms: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906); 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions (0426, 1610); 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry; 0426 Biogeosciences: Biosphere/atmosphere interactions (0315). Read Full Article (file size: 174876 bytes) Cited by Citation: Spracklen, D. V., J. A. Logan, L. J. Mickley, R. J. Park, R. Yevich, A. L. Westerling, and D. A. Jaffe (2007), Wildfires drive interannual variability of organic carbon aerosol in the western U.S. in summer, Geophys. Res. Lett., 34, L16816, doi:10.1029/2007GL030037. Copyright 2007 by the American Geophysical Union.

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